Textile treatment compositions suitable for providing fabric softening and static control benefits during laundering are well-known in the art and have found wide-scale commercial application. Conventionally, rinse-added fabric softening compositions contain, as the active softening component, substantially water-insoluble cationic materials having two long alkyl chains. Typical of such materials are ditallow alkyl dimethyl ammonium chloride and imidazolinium compounds substituted with two stearyl or tallow alkyl groups. These materials are normally prepared in the form of a dispersion in water.
It is highly desirable to prepare physically-acceptable textile treatment compositions containing biodegradable, water-insoluble, softener materials that exhibit excellent softening performance. However, materials which are biodegradable are often difficult to formulate as stable liquid compositions, especially at high concentrations.
The use of various quaternized ester-ammonium salts as cationic fabric softening agents is known in the art. For example, U.S. Pat. No. 4,339,391, Hoffmann et al., issued Jul. 13, 1982, lists a series of quaternized ester-ammonium salts which function as fabric softeners. Various quaternized ester-ammonium salts are commercially available under the trade names SYNPROLAM FS from ICI and REWOQUAT from REWO.
In addition, diester quaternary ammonium salts as fabric softeners are known in the art. For example, U.S. Pat. No. 4,137,180, Naik et al., issued on Jan. 30, 1979, relates to diester quaternary ammonium salts free of or containing less that 5% of monoester quaternary ammonium salts as a fabric softening compound.
E.P.A. No. 409,502, Tandela et al., published Jan. 23, 1991, discloses fabric softening compositions comprising biodegradable diester quaternary ammonium compounds and fatty acids which are added to boost the softener performance.
E.P.A. No. 409,503, Tandela, published Jan. 23, 1991, relates to biodegradable fabric softener compositions with an amine softener, fatty acid, and preferably a buffer acid. Anti-redeposition agents are optional. The reference teaches that the amine should be protonated to reduce the unwanted effects of anionic actives carried over from the main wash. The amine and buffer acid have a molar ratio of 5:1 to 1:10, preferably from 1:1 to 1:10. Preferred formulations may also contain fatty ethoxylated materials as performance boosters.
E.P.A. No. 409,504, Singh et al., published Jan. 23, 1991, relates to a biodegradable fabric softening composition comprising a diester quaternary ammonium material and an extender to minimize unacceptable thickening upon standing. The extender can be monoesters of polyethylene glycol of molecular weight between 200 and 2000. Anti-redeposition agents at up to 5% by weight are optional.
Similarly, methods for preparing various quaternized esteramine compounds are known in the art. See, for example, U.S. Pat. No. 3,342,840, Sobolev, issued Sep. 19, 1967, U.S. Pat. No. 3,872,138, Ogatu, issued March 18, 1975, and Japanese Laid Open Publication 49-1510, assigned to Gosei Chem. Ind. Co., published Jan. 9, 1974.
Various solutions to the problem of preparing concentrated fabric softening compositions suitable for consumer use have been addressed in the art. See, for example, U.S. Pat. Nos. 4,426,299, issued Jan. 17, 1984, and 4,401,578, issued Aug. 30, 1983, Verbruggen, which relate to paraffin, fatty acids and ester extenders in softener concentrates as viscosity control agents.
European Pat. No. 0,018,039, Clint et al., issued Mar. 7, 1984, relates to hydrocarbons plus soluble cationic or nonionic surfactants in softener concentrates to improve viscosity and stability characteristics.
U.S. Pat. No. 4,454,049, MacGilp et al., issued Jun. 12, 1984, discloses concentrated liquid textile treatment compositions in the form of isotropic solutions comprising water-insoluble di-C.sub.16 -C.sub.24 optionally hydroxy-substituted alkyl, alkaryl or alkenyl cationic fabric softeners, at least about 70% of the fabric softener consisting of one or more components together having a melting completion temperature of less than about 20.degree. C., a water-insoluble nonionic extender, especially C.sub.10 -C.sub.40 hydrocarbons or esters of mono- or polyhydric alcohols with C.sub.8 -C.sub.24 fatty acids, and a water-miscible organic solvent. The concentrates have improved formulation stability and dispersibility, combined with excellent fabric softening characteristics.
U.S. Pat. No. 4,439,330, Ooms, issued Mar. 27, 1984, teaches concentrated fabric softeners comprising ethoxylated amines.
U.S. Pat. No. 4,476,031, Ooms, issued Oct. 9, 1984, teaches ethoxylated amines or protonated derivatives thereof, in combination with ammonium, imidazolinium, and like materials.
The use of alkoxylated amines, as a class, in softener compositions is known (see, for example, German Patent Applications 2,829,022, Jakobi and Schmadel, published Jan. 10, 1980, and 1,619,043, Mueller et al., published Oct. 30, 1969, and U.S. Pat. Nos. 4,076,632, Davis, issued Feb. 28, 1978, and 4,157,307, Jaeger et al., issued June 5, 1979).
U.S. Pat. No. 4,422,949, Ooms, issued Dec. 27, 1983, relates to softener concentrates based on ditallow dimethyl ammonium chloride (DTDHAC), glycerol monostearate and polycationics.
In United Kingdom Application 2,007,734A, Sherman et al., published May 23, 1979, fabric softener concentrates are disclosed which contain a mixture of fatty quaternary ammonium salts having at least one C.sub.8 -C.sub.30 alkyl substituent and an oil or substantially water-insoluble compound having oily/fatty properties. The concentrates are said to be easily dispersed/emulsified in cold water to form fabric softening compositions.
Concentrated dispersions of softener material can be prepared as described United Kingdom Patent Specification 1,601,360, Goffinet, published Oct. 28, 1981, by incorporating certain nonionic adjunct softening materials therein.
As can be seen, the various solutions to the specific problem of preparing fabric softening compositions in concentrated form suitable for consumer use have not been entirely satisfactory. It is generally known (for example, in U.S. Pat. No. 3,681,241, Rudy, issued Aug. 1, 1972) that the presence of ionizable salts in softener compositions does help reduce viscosity.
Ethoxylated amines having clay soil removal and anti-redeposition properties, which are incorporated into detergent compositions, are known in the art. See, for example, U.S. Pat. No. 4,597,898, Vander Meet, issued Jul. 1, 1986; U.S. Pat. No. 3,929,678, Laughlin et al., issued Dec. 30, 1975 (detergent composition containing polyethoxy zwitterionic surfactants with detergent builders); U.S. Pat. No. 3,719,647, Hardy et al., issued Mar. 6, 1973 (copolymers of acrylic or mothacrylic acid with acrylic or mothacrylic acid-ethylene oxide condensates); U.S. Pat. No. 3,597,416, Diehl, issued Aug. 3, 1971 (cellulose and carboxymethylcellulose derivatives); U.S. Pat. No. 3,523,088, Dean et al., issued Aug. 4, 1970 (alkali metal carboxymethylcellulose and hydroxypropylcellulose); and U.S. Pat. No. 4,228,044, Cambre, issued Oct. 14, 1980 (detergent composition with nonionic alkyl polyethoxy surfactant, polyethoxy alkyl quaternary cationic surfactant and a fatty amide surfactant).
Copending U.S. patent application Ser. No. 07/693,493, Vogel, Watson, Wahl and Benvegnu, filed Apr. 30, 1991, teaches softening compositions containing imidazoline mixtures with ethoxylated materials as scum dispersants.
All of the above patents, patent applications, and publications are incorporated herein by reference.
It has now been discovered that fabric softener compositions containing certain diester quaternary ammonium fabric softener materials interact with anionic surfactants and detergency builders that are carried over into the rinse cycle to form surprisingly high levels of undesirable scum. This invention provides a way to avoid the formation of scum without compromising the, e.g., biodegradable benefits and/or good fabric softening performance of the diester quaternary ammonium materials.
It is a preferred object of this invention to provide an effective, storage-stable, biodegradable fabric softening composition in the form of a liquid concentrate. It is a further objective to provide a softener composition which reduces scum formation in the washer rinse cycle and resulting deposition on fabrics and washer drums.